Cardiac sympathetic afferent reflex responses to epicardial application of adenosine is enhanced in dogs with heart failure

Adenosine is an endogenous metabolite capable of stimulating cardiac sympathetic afférents. The purpose of this study was to compare cardiac sympathetic afferent reflex responses to epicardial application of adenosine. Ventricular pacing was carried out in 7 dogs until signs of HF were evident. Eight sham dogs served as controls. At the time of the acute experiment the dogs were anesthetized with chkjratose. The mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve (RNA) responses to left ventricular application of adenosine (200 pg in 0.5 ml] were determined in the sino-aortic denervated and vagotomized state. The responses to adenosine are shown in the table below. Change in MAP(mmHg) RNA (% of CM) HR(BPM) Sham 0.8 ±1.9 7.212.1 0.6 ±0.4 HF 1.3 ±0.7 15.9±1.7' 1,4 ±0.4P<0.05, compared with sham group. These enhanced cardiac sympathetic afferent reflex responses to adenosine were more sensitive after adenosine re-uptake blocker, dipyridamole (0.6 mg/kg, iv) in the heart failure group and could be prevented by the adenosine receptor antagonist, aminophyllin (5 mgAg, iv). These data suggest that there is an enhancement of the reflex response to topical application of adenosine in dogs with HF.